#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
    int n = 0;
    scanf("%d", &n);
    double ret = 0;
    for (int i = 1; i <= n; i++)
    {
        ret += (1.0 / i);
    }
    printf("%.6lf", ret);
    return 0;
}